In general, a condensing sheet used in a liquid crystal display includes a base layer 60, and a linear prism 50 that is formed on the base layer 60 and has a triangular section, which is shown in FIG. 1. However, the condensing sheet is disadvantageous in that it is difficult to control a viewing angle and to improve optical performance such as condensing efficiency and contrast because light L2 incident at an ineffective angle shown in FIG. 1 causes sidelobes.
In order to avoid the above-mentioned disadvantages, a condensing sheet that includes a base layer 20, a light output unit which is formed on an upper side of the base layer 20 and has a lens 30, and a light input unit 10 which is formed on a lower side of the base layer 20 and includes a protrusion 11b and a reflector 12b is shown in FIG. 2.
In the condensing sheet of FIG. 2, since light L1 that is incident at an effective angle passes through the lens 30, and light L2 that is incident at an ineffective angle is recycled by using the reflector 12b, condensing may be performed at an effective angle to relatively improve light efficiency. However, if a current printing process for forming the reflector 12b is used, that is, if a printing process on a flat surface of the protrusion 11b (FIG. 3) and a process of performing exposure by using a photomask and then removing a penetration unit 13 (FIG. 4) are used, as shown in FIGS. 3 and 4, the printing is performed so that thicknesses 12s of both sides of the reflector 12b are smaller than the thickness 12t of the center of the reflector. Thus, light loss occurs in the light input unit 10 during the radiation of light L2 that is incident at an ineffective angle. That is, light L2 that is incident at an ineffective angle does not reflect by the reflector 12b but passes through the protrusion 11b. 
In order to maximize light efficiency of the light input unit 10, pigments such as TiO2, Al2O3, and BaSO3 are added to ink that constitutes the reflector 12b and is made of a UV-curable polymer resin or a thermosetting polymer resin in a predetermined amount in FIG. 5, or are applied to a predetermined thickness in FIGS. 6 and 7 to perform reflection. Thereby, reflectivity and hiding power are improved. However, if the reflector 12b is printed by using a current printing process, as shown in FIGS. 3 and 4, the thicknesses 12s of both sides of the reflector 12b are small, thus reducing the reflectivity and hiding power of both sides of the reflector 12b. 
Specifically, if the reflector 12b is printed on the flat protrusion 11b having a rectangular section by using a printing process such as gravure printing, offset printing, silk screen printing, and inkjet printing, as shown in FIG. 3, the reflector 12b is printed so that both sides of the reflector 12b have the small thickness 12s. Since both sides of the reflector 12b have the small thickness 12s, significant light loss occurs. If a large amount of pigment is mixed with the ink in order to improve reflectivity, it is difficult to perform uniform printing due to agglomeration resulting from poor dispersion of the pigment or the impurity, which is shown in FIG. 13.
In FIG. 4, a printing process using photomask exposure has a disadvantage in that a penetration unit 13 needs to be removed after the exposure. Accordingly, a clear printing line is not formed and it is difficult to ensure a good appearance. Furthermore, since it is difficult to form the fine penetration unit 13 having the size of 40 microns or less and to print the reflector 12b having a desirable thickness, it is difficult to improve reflectivity and wear resistance of the reflector 12b is reduced. Therefore, it is difficult to optimize the quality and production cost is increased due to an exposure process.
In the reflector 12b of FIGS. 3 and 4, since the thickness 12s of each of both sides is small as compared to the thickness 12t of the center, when light L2 is incident on both sides of the reflector 12b at an ineffective angle, the intensity of reflection light is relatively weak and the intensity of penetration light is relatively strong, thus reducing hiding power.
The weak intensity of reflection light means that the intensity of light capable of being reused at an effective angle is weak. The occurrence of light that penetrates the reflector 12b at an ineffective angle means that a loss of light occurs at an ineffective angle.
If both sides of the reflector 12b having the small thickness 12s have reflectivity that is the same as or larger than that of the center of the reflector 12b having relatively large thickness 12t, reflection efficiency can be optimized. However, in FIG. 6, even though the different reflectors have the same amount of pigment, the small thickness significantly reduces the reflectivity.
Additionally, when an excessive amount of pigment such as TiO2 is added in order to increase the reflectivity in respects to the same thickness, dispersion of the pigment is poor during the printing process, causing agglomeration of pigment particles. Thus, it is difficult to perform the uniform printing and to increase the reflectivity, which is shown in FIG. 5.
Therefore, in respects to the condensing sheet containing the reflector, there is a need to develop a structure and a method of preventing the above-mentioned problems and improving light efficiency of the light input unit, physical properties such as wear resistance, and uniformity.